Irradiation-Thermal-Mechanical Coupling Behaviors of a Typical TRISO/SiC Fuel Element Based on Actual Distribution

Abstract TRISO (Tristructural isotropic)/SiC Fuel Elements is developed and considered a kind of high-temperature gas cooled reactor (HTGR) fuel, it helps to improve the safety, competitiveness, and economics of commercial nuclear power. This study focuses on a typical fuel element, which is manufactured by ceramic SiC and contains more than 10000 surrogate TRISO particles. Then the actual position information of particles is applied in finite element analysis. The finite element model, considering comprehensive coupling behavior (including irradiation-induced dimensional change, irradiation-induced creep, thermal expansion, fission gas pressure, heat generation and conduction, elasticity and plasticity, etc.) and particle to particle/particle to matrix interaction, were developed based on the COMSOL platform and accurately verified. The verification process mainly based on the IAEA benchmark of single TRISO particle, a three-layer model and the fission gas release result using BISON. Based on the single particle model, a more complicated FEM is considered. It provides detailed modeling and analysis of the performance of each layer, which may occupy a huge amount of computing resources. Therefore, representative volume element (RVE) is selected, modeling the geometric structure with symmetry. The result indicated there is a significant high stress in the densely packed areas of fuel element, which increased the failure possibility of particles. By analyzing the stress field, temperature field and deformation of the model, it is indicated that in order to reduce the failure possibility of TRISO particle, the particle clusters should be avoided during fabrication process.